Spatial audio effects (also known as 3D audio effects) are a group of sound effects that manipulate sound produced by stereo speakers, surround sound speakers, speaker arrays or headphones for virtual placement of sound sources anywhere in a three-dimensional space including behind, above or below a listener. Spatial audio processing generally includes transforming sound waves using head-related transfer function (HRTF) to mimic natural sounds which emanate from a point in three dimensional space. The HRTF describes how a sound from a specific point will arrive at a listener's ear. A pair of HRTFs for two ears can be used to synthesize a binaural sound that seems to come from a particular point in space. By simulating the placement of a sound source in a 3D space, spatial audio effects enable a listener to identify the location or origin of a sound in direction and distance. This is often referred to as sound localization.
Sonification is the use of non-speech audio to convey information or perceptualize data. Sonification of data generally includes altering various components of a sound as a function of the information to be conveyed in order to change the user's perception of the sound, and in turn, their perception of the underlying information being portrayed.